Certain principles of studying the heart at necropsy are summarized. 1) Do not except under quite rare circumstances, open the heart when it is fresh. After excising the heart at necropsy, fix it in formalin. 2) X-ray the heart after fixation if cardiac disease is thought to be present. Of course, postmortem clot and the crumbled bits of paper should be removed from the intact specimen before radiographs are taken. 3) The method used to open the heart is determined by the type of cardiac disease that is present or suspected.